The invention relates to a power transmission system and more particularly a continuously variable transmission including a low-inertia disk or wheel which is tractionally driven by drive rotors. The invention may further use a multi-range gear system to extend the output speed range of the drive system, which is engaged in differential parallel arrangement with the disk and synchronized therewith for controlling acceleration and deceleration of output from the transmission.
Continuously variable drive systems of various types have been developed in an effort to provide a commercially acceptable transmission which allows a wide range of speeds to be achieved over a continuous range. It is commonly recognized that continuous variation of speed ratios can provide significant improvement in efficiency of a motor vehicle engine, and therefore result in improved fuel economy. Continuously variable transmissions are also used in a variety of other applications to provide a continuous variation of speed over a given range.
In motor vehicles having a continuously variable transmission system, the power transmitted by the vehicle engine to the wheels will pass through a variable ratio transmission, which in turn must be able to withstand the high torque and other conditions encountered. Several types of continuously variable drives have been developed, including traction drives and V-belt continuously variable drives which rely on belts and moveable pulleys. Prior systems have encountered significant problems including rapid fatigue and failure of main components, insufficient power density, a limited speed range, unstable ratio control, excessive cost or other problems which have not been adequately solved for commercial use of such systems to a wide extent. There is therefore a pressing need for a continuously variable transmission which overcomes these problems and can be produced cost effectively.